Interstate 485 outerbelt jams persist, but extra capacity unused

The state’s recent $82 million widening of Interstate 485 in south Charlotte has improved traffic flow, but the highway still can bog down at rush hour.

There is enough asphalt in place today to add a new lane, but the N.C. Department of Transportation has no plans to use that extra space for at least five years.

One reason: Using the lane today would make it difficult to convert it to a toll lane at the end of the decade.

“The DOT knows they can’t make a free lane a toll lane later, so they will leave it unstriped, to somehow protect it,” said David Hartgen, a transportation consultant and former UNC Charlotte professor. “Citizens will see wasted pavement, or vacant pavement, and ask, ‘Why are we waiting later when we need the capacity now?’ ”

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Before the widening project, I-485 was one of the state’s most congested highways. Roughly 120,000 vehicles traveled on that stretch of highway, which was usually restricted to two lanes each way.

The widening project added a lane each way from I-77 to Rea Road, a 9.2-mile stretch.

When the highway was widened, the contractor, Lane Construction, created enough space to add a fourth lane in each direction. The asphalt has already been laid, but the extra space is cordoned off by orange barrels.

Adding a new lane from I-77 to Johnston Road would be simple. The shoulder is narrower from Johnston Road to Rea Road, and creating a fourth lane likely would require a small shifting of all lanes toward the outer shoulder.

Traffic now flows for much of the day, but at peak rush hour, the highway can get clogged. In 2018, the state plans to start a second widening project on I-485. The DOT will add an express toll lane from Rea Road to U.S. 74. It also will convert that empty lane that’s not in use today into a toll lane.

Why not use the lane today?

If a highway is built with federal money, the U.S. DOT prohibits states from converting general-purpose lanes to toll lanes. There are some exceptions.

So if the N.C. DOT opened up the lane today, it might be politically difficult to toll the lane in the future.

Another option

Although the U.S. DOT generally frowns upon converting free lanes to toll lanes, the state has another option: Opening up the lane today as a carpool lane and then tolling it in the future.

That’s what the state is doing on I-77 in north Charlotte. The N.C. DOT is converting the existing high-occupancy vehicle lane into a toll lane.

Adding a carpool lane to I-485 would be straightforward. Because of the cold weather, Lane Construction hasn’t finished laying a final layer of asphalt and striping the highway. That will happen in the spring.

The state could easily paint the highway to include a new toll lane.

Warren Cooksey of the N.C. DOT said adding a carpool lane might be more difficult than it appears. The state would have to hold public meetings and possibly receive federal approval. “Then we are talking about it being an HOV lane for a year or two,” he said. “I’m not sure it’s worth it.”

Cooksey said he recently drove part of the new outerbelt at 5:20 p.m. and went 55 mph. “The lanes provided noticeable and measurable relief,” he said.

Would a new lane help?

Cooksey said the state’s research shows that the carpool lane on I-77 north provided little relief, handling 600 cars an hour. He said he doesn’t think a carpool lane on I-485 would do much for the project.

A carpool lane, however, would carry more cars than a lane that’s not used.

City Council member Ed Driggs, who represents the Ballantyne area, said he asked the DOT why it couldn’t use the extra lane now. He said he was told it was because it needs to reserve the lane for a toll lane.

Driggs said creating a temporary carpool lane could be a good idea. But he said he’s concerned that some of the traffic problems are caused by backups at exits, such as Johnston Road. An extra lane might not help that problem.

The state hasn’t done any detailed traffic studies of how the widening has had an impact on traffic. It’s possible the interstate is handling new trips that might previously had been commuted on smaller city streets.

And some of the problem may be on the outer loop at Rea Road, where the highway goes from three lanes to two. A fourth lane ending at Rea Road also could slow traffic, as more people have to slow to merge.